We propose to develop and validate an ultrasound-based imaging approach to image guided hyperthermia cancer therapy. High intensity focused ultrasound (HIFU) has shown considerable promise in recent years as a tool for successfully treating a range of cancers. HIFU is limited however by difficulties in noninvasively monitoring the progress of the treatment to control the size, shape, and extent of the thermal lesion. The objective of the work here is the development and initial validation using commercial instrumentation of a new approach by which ultrasonic imaging can be used to guide HIFU treatment. We have assembled a university-industrial consortium led by Northeastern University and comprised of participants from Analogic Corporation, Boston University, and the National Center for Physical Acoustics at the University of Mississippi. The research plan calls for a balanced distribution of the effort across the four members of the team. Technically, we consider a model-based approach to the problem of lesion characterization wherein the data collected by the imaging transducer are used to estimate parameters directly related to the size, shape, location, orientation, and contrast of the HIFU-induced lesion. Our initial results indicate the ability of this method to identify lesion-like regions under carefully controlled experimental conditions. We propose here to build on this effort both in terms of : 1/ more extensive phantom and ex vivo experimental evaluation; 2/ the development and experimental evaluation of new imaging methods capable of addressing realistic HIFU monitoring scenarios including multi-lesion imaging and tracking of lesion formation; and 3/ initial implementation of all methods to state-of-the-art hardware platforms for eventual use in real-time treatment monitoring. Validation of the performance of the lesion characterization algorithms and the utility of the optimization approaches will take place using state-of-the-art ultrasound imaging instrumentation built by Analogic. We provide concrete plans concerning the migration of the work in this project to the clinic. [unreadable] [unreadable] [unreadable]